138 CHYMISTRY APPLIED TO AGRICULTURE. 



traded is fleshy, and of a loose, spongy texture, it can be 

 reduced to a pulp by means of a press; the juice thus 

 expressed deposits the fecula, which must be very carefully 

 washed, in order that the noxious principles contained in 

 it may be perfectly separated. The whiteness and ex- 

 cellence of the fecula depends upon its being thoroughly 

 washed. 



Fermentation is the means most commonly employed 

 for extracting starch from grain ; but this operation will 

 produce only alcohol, if care be not taken in mixing the 

 acid with the grain, to prevent the spirituous fermentation. 

 This acid is made by mixing with a bucket of hot water 

 two pounds of baker's yeast, to which is added, two days 

 after, several buckets of hot water ; in forty-eight hours 

 from that time the acid will be sufficiently developed. 



This acid, which is called by the starch manufacturers 

 sure water, contains nothing but vinegar, and I therefore 

 presume, that the acetic acid may be used with the same 

 success. 



In order to extract the starch by fermentation, a bucket 

 of this sure water is thrown into a hogshead having one 

 end taken out. The hogshead is then filled half full of 

 common water, into which flour is stirred till it is full ; 

 the whole is then left to macerate during ten days in 

 summer, and fourteen in winter. The sufficiently ad- 

 vanced state of the maceration may be known by a de- 

 posit being formed, and the liquor swimming above it re- 

 maining clear, whilst the surface is covered with foam or 

 fat water. The water and foam is drawn off", and the 

 deposit is thrown into a sack of hair-cloth, which is placed 

 in a tub, and water thrown over it till it runs off" without 

 any cloudiness. The substance remaining in the bag, 

 which is only the coarsest part, serves as food for cattle. 

 At the end of two or three days, the water floating above 

 the deposit formed in the tub is drawn off*, and a part of it 

 preserved to serve as sure water, for succeeding operations. 



In order to have good starch, the deposit must be wash- 

 ed in a great deal of water and well mixed ; two or three 

 days after, the water for the remaining washings may be 

 thrown on. 



The deposit which is formed presents three layers differ- 

 ing widely in their quality ; the first is principally com- 

 posed of fragments, and is taken off* as food for cattle, or 

 to fatten hogs with. The second layer is generally formed 



